The present invention is directed to apparatus for dispensing two-or-more-component adhesives, sealing compounds, putties, grouts, coatings and the like. The reactive components are separated within the chamber of the device by barriers formed as reaction products of the components. During dispensing these "reacted barriers" are trapped by the novel nozzle so that they do not clog the exit orifice of the device. This invention is particularly useful for dispensing epoxy, polyurethanes and polyester resins used to secure bolts in boreholes in construction applications.
Plural component adhesive systems are highly desired because of the ability to tailor properties of the final product. For example, viscosity, cure rate, green and final strength can be controlled by varying one or more components. The components must be thoroughly mixed during dispensing for plural component systems to be effective, however. Mixing is usually difficult in hand-operated equipment due to the high viscosity of the components and substantial pressure drop across any static mixing devices employed.
Static mixers are known to provide thorough mixing of multi-component adhesive resins. U.S. Pat. No. 4,538,920, for example, teaches a multi-barreled dispensing device including a static mixing element. The static mixer is an elongate convoluted member housed within the bore of the exit nozzle of the device. Incoming resin streams are mixed by the mixing blades of the static mixer and emerge thoroughly mixed therefrom.
The use of multi-component cartridges is well known. Each component must be kept physically separated from each of the others in order to avoid chemical reactions therebetween. The aforementioned U.S. Pat. No. 4,538,920 teaches separate tubes or "barrels" for each of the components. U.S. Pat. No. 4,493,436 relates to a compartmental cartridge having a barrier wall separating components. The barrier wall is stored, during dispensing, in the evacuated portion of the cartridge.
A further method of separating components in a cartridge is the provision of "reacted barriers" therebetween. For example, resin and hardener of a two-part epoxy adhesive system may be carefully placed within a cartridge. A thin wall of reaction product forms therebetween and serves to isolate the components from each other. U.S. Pat. No. 3,915,297 relates to a cartridge containing polyester resin and catalyst which are separated by a polymerized (reacted) interface.
While the reacted barrier-type cartridges offer advantages over other styles of multi-chambered cartridges, dispensing product therefrom is complicated by the presence of the barrier skin. This skin can dislodge and clog the output orifice of the dispenser. Accordingly, it is one object of the present invention to provide an improved cartridge which (1) provides a constant mix profile among multiple components, (2) thoroughly mixes components of a multi-component cartridge, (3) traps reacted barriers to avoid clogging of the mixer and/or output orifice and (4) requires relatively less pressure, in order to hand-dispense its product, than known devices.